What is an indicator of natural increase in a population?

Natural increase in a population refers to the growth that occurs when the number of births exceeds the number of deaths over a specific period. Therefore, the balance of births and deaths serves as a direct indicator of natural increase. If the birth rate is higher than the death rate, the population will experience natural growth. Conversely, if the death rate surpasses the birth rate, the population may decline.

The other options relate to various environmental, economic, or social factors but do not specifically reflect the direct demographic changes that contribute to natural increase. For instance, the amount of resources available can impact population growth by affecting living conditions and the ability to sustain a larger population, but it does not measure the births and deaths themselves. Similarly, economic conditions can influence population growth, usually through factors like migration and fertility rates, but they do not directly indicate natural increase. The average area of land per person provides context about population density and resource distribution rather than demographic changes linked to natural increase.